Very long term changes in CNS activity likely reflect changes in neurons at the genomic level. We intend to study steroid hormone action on the nervous system as a model for how specific changes in genomic activity can bring about changes in the behavior of an organism. The system involves the action of the steroid hormones, the ecdysteroids, on the nervous system of the hawkmoth, Manduca sexta. These steroids induce a process, termed molting, which involves the production of a new exoskeleton followed by the shedding (ecdysis) of the old one. The latter behavior is triggered by a neuropeptide, eclosion hormone (EH), on the CNS, but the peptide can only act on nervous systems that have been "primed" by exposure to ecdysteroids. Our data to date suggests that the steroid primes the CNS by causing de novo synthesis of 2 endogenous phosphoproteins that mediate the response of target neurons to EH. This proposal will examine the mechanism by which ecdysteroids induce these proteins (the EGPs) and the role the EGPs play in mediating the ecdysis response. We will prepare antibodies to the EGPs and then using immunocytochemistry determine which cells contain the EGPs. These cells will be examined to see if they bind and respond to EH. If possible specific EH target cells will be injected with the antibodies to diminish the response to EH. The origin and regulation of the EGPs will also be studied. Our hypothesis is that ecdysteroids induce their de novo synthesis. We intend to study their synthesis using in vitro labeling followed by precipitation of the labeled EGPs with the antibody. The time of appearance of the appropriate mRNAs will also be determined using a cell free translation system and the relationship of protein and RNA synthesis to 20-HE exposure examined.